Production of lead powder



June 5, 1934.

Filed July 25, 1930 5 sheets-smet 1 IN VEN TOR. .lf-3f IIs/1 m um M W ATTORNEYS.

June 5, 1934. l.. s. lsHlMuRA PRODUCTION oF LEAD POWDER Filed July 25,1930 5 Shegts-sheet 2 ATTORNEYS.

`Ivune 5, 1934.

` Filed July 25,'1330 L. s. Isl-"MURA H loDucTloN 0F' LEAD POWDER Y l 5sheets-sheet 3l ATTORNEYS.

' June 5,1934.'

5 Sheets-Sheet 4 Filed July z5,` 1930 June 5,v 1934.

L. s. ISHIMURA 1,961,296 PRODUCTION OF LEAD POWDER Filed July 25, 1930 5Sheets-Sheet 5 ATTORNEYS.

Patented June `5, 1934 UNITED STATES PArsNr OFFICE 1,961,296 PRODUCTIONOF LEAD POWDER Lyuho S. Ishimura, Kamikyo-ku-Kyoto, Japan ApplicationJuly 25,1930,`Serial No. 470,652

10 Claims. (Cl. 23146) This invention relates to the production of apowder specifically lead suboxide powder in an extremely dry and nestate of subdivision.

One object of the invention is to carry forward and improve certainfeatures disclosed in the application of Shimadzu No. 104,999, led

April 27, 1926, Patent No. 1,896,020 issued Jan.

Generally spealnng, the rst of my improvements relates to the treatmentof, crude lead before it reaches the oxidizing mill.

Another object of the invention isto prevent the air forced into atumbling mill from backing out through the mill entrance or hopper andthus impregnating the atmosphere in the room where the mill is locatedwith the fine powders since these powders particularly lead powders aremore or less injurious to the health of the mill operators.

Another improvement in the invention relates to the treatment of thepowder, .particularly lead suboxide powder, after it leaves the mill.

With this general statement of the objects of the invention I will nowproceed to describe the same in connection with the attached drawings inwhich,

Figure lis a more or less diagrammatic illustration partly in section ofthe entire layout of my apparatus;

Figure 2 is a view partly in section of my apparatus for melting andforming the lead into bars;

Figure 3 is a plan View, partly broken away, of the mold for forming thelead into bars and feeding the bars to a cutter preparatory to cuttingthe lead into lumps;

Figure 4 is a View, partly in section, of the lead cutter, the millhopper and the conveyor for carrying the lead lumps from the cutter tothe entrance of the mill;

Figure 5 is a sectional view of the cutter and rollers for feeding alead strip to the cutter and the mill hopper for receiving the cutlumps;

Figure 6 is a perspective view of the lead cutter,

Figure 7 is a view partly in section showing the interior apparatus ofthe mill the dust col.

lecting and powder removing apparatus;

Figure 8 is a view showing a modified form of air inlet.

Referring more particularly to Figures 1 and 2, there is shown at theright of each figure, a vessel in which the lead is melted and fromwhich the lead issues through a spout 1 into a groove or channel 9 onthe upper surface of a wheel 2 over which Vcooling water may be made toflow through a pipe marked water pipe, in yFigure 1. The water may issuefrom an outlet 3 into a vessel 4 from which it may run through a spout5. l,

The lead is melted by means of an ordinary burner 6 and since thetemperature of the melted lead should be kept more or less uniform,

a thermometer 7 is attached to the melted lead to indicate itstemperature.v The melting pot` or vessel may have at its bottom anoutlet valve to permit and regulate the ow of the lead from the vessel.

As the lead issues from the spout 1, 'it empties i into a groove l9 inthe wheel 2 and the wheel 2 70 is continuously revolved lby means ofpower applied to a shaft 10 which operates through bevelled gears and ashaft 11 to turn a toothed, pinion -13. On the lower perimeter -of thewheel- 2 cogs or teeth may be formed adapted to mesh 75 with the pinion13 and the turning of the pinion 13 would cause the wheel .2 to revolvein an anticlockwise direction as shown in Fgure 3.

The lead bar formed in the groove 9 as the 80 wheel 2 revolves, iscarried to a scoop 14 having a pointed end 15 to extend into the groove9 and as this scoop is rearwardlyy and upwardly inclined, from thegroove 9, as shown I best in Figure l, the end of the lead bar formed inthe groove 9 would be carried up over a platform 16 to and betweenrollers 17, 18, Figure 1, to rollers 19, 20, Figure 5. Rollers 19, 20may be driven from 4any convenient train of operating mechanismextending from the source of power or by an independent source of powerand an uppery and lower roller pull the lead bar between them and feedit to the cutter, although I preferably provide another set of rollers19', 20 to assist in keeping the lead bar moving at 95 a uniform speedto the cutter 22 and to insure uniform pressureon the lead bar I mayprovide springs 17 and 18' above rollers 19 'and 19 respectively.

The lead bar, after leaving the rollers 19', 100 20', passes over ablock 21 to the cutter 22. This cutter shown in perspective in Figure 6preferably has a cam shaped periphery with a sharp edge 23 and iscontinuouslyv revolved to out lumps Aof lead from the lead bar as thebar is continuously fed to the cutter as indicated in Figures 1 and 5.

The lead lumps, as they are cut off, fall into a hopper 23 stationarilysupportedon a standard or base frame 25, Figure 4. The mill 26 is 110supported between the two standards and 29 on trunnions 30-31 and mayhave therein a pyrometer 63. The mill may be revolved by any convenientmechanism as by means of a toothed pinion 32 operating from anyconvenient source of power, the mill having on its ex'terior a toothedring 34. Inside the trunnion 31 there is formed a worm conveyor bestshown in Figure 4, whichas the trunnlon 31 revolves, carries the leadfrom the stationary hopper 23, Figure 4, to the interior of therevolving mill 26.

As the cut lumps, of lead are tumbled over and over when the mill 26 isrevolved, air is forced through a stationary pipe 35 extending axiallythrough the worm conveyor in trunnion 31 to blow out the powderresulting from the lumps of lead rubbing against each other.

The part of the pipe 35 enclosed in the mill may be made in sections 35connected by couplings 36. From each coupling extends a nozzle 37 andthe pipe 35 preferably ends in a nozzle 38 terminating at the expandedend of the trunnion 30, Figure 7.

As the air is blown through the pipe 35, it passes down throughthenozzles 37 and around the lumps of lead and as the mill revolves thefinely divided powder is lifted and blown from around and between thelead lumps and the air issuing from nozzle 38 blows the powder out ofthe mill 26, through the trunnion as soon as the surfaces of the lumpsare oxidized and the powder rubbed oi by the tumbling action in themill.

As the air passes through the pipe into the mill it produces more orless pressure in the mill and causes the air laden with the dust to tendto back out through the trunnion 31 and hopper 23 into the room in whichthe mill is located. To prevent this powder or dust laden air passingback through the trunnion 31 and hopper 23 and out into the room, Iprovide nozzles 40 inclined as shown towards the mill. It is apparentfrom the construction, best shown in Figure 4, that the "air underpressure in the pipe 35 and issuing through the inclined nozzles 40 asshown causes an induced draft in the trunnion which will blow any dustthat might tend to back out from the mill to the hopper 23, back intothe mill and thus prevent this dust from passing up out of the hopper 23into the room in which the mill is located and cause it all to be blownby nozzles 37 and 38 outwardly through the trunnion 30. In this way Ihave successfully prevented the dust in the mill from passing backthrough the trunnion 31 and hopper 23 to contaminate the air in the roomin which the mill is located. This arrangement eliminates allcomplicated mechanically operated valves that would be necessary tofulfill the purpose otherwise. VA pyrometer 63 of which the thermocoupleis suitable placed/inside of the mill 26 as shown in Figure 7, indicatesthe Working temperature of the mill and is useful in controlling thetemperature to keep it within desired limits. It.being understood thatthe temperature in the mill may be varied by varying the speed at whichthe mill is run or the speed at which the lead lumps are fed to themillor by varying the air supply.

The dust laden air from the mill 26 passes into a powder collecting andcooling apparatusy 45, Figures 1 and 7. This apparatus preferablycomprises a vessel into which the air enters and most of the powder isdeposited in the bottom of the vessel 45.

I preferably water jacket the lower part of the vessel and supply waterthereto in any convenient way, as through a pipe 47. The

(water` jacket around the lower part of the vessel ytends to cool thelead powder which is composed largely of lead suboxide and pure lead andprevents rapid oxidation thereof and in the lower part of the waterjacketed portion 48, I provide a screw conveyor 49 which may be run'from any source of power to quickly pass the powder from the waterjacketed portion 48 to an outlet 50 which may be conveniently covered bya valve 51 held normally to its seat around the outlet by a counterweight 52.

The screw conveyor 49 is made longer at the discharge end so that thepowder filling the spaces toward that end counter balances the pressureexisting in the collector 45 and prevents the powder from blowing outdue to such a pressure. f

I may also arrange a pyrometer 62 so as to indicate the temperature ofthis collecting chamber.

In the lupper portion of the vessel 45, I may provide dust collectingbags 53, 54, 55 attached at their bottom in any convenient way to thevessel 45 to produce an air tight connection between the bottom of thebags and the vessel 45. The bags may be hung closed end up from asupport 58 by hooks or otherwise and the vessel 45 enclosing the bagsmay have a cone shaped cover with an outlet 60 to which a fan 61, Figure1, may be connected to draw out the air from the vessel 45. The bags 53,54, 55 being made of fabric and attached air tight at their bottoms toVessel 45, allows the air to pass through the fabric but said bags stopthe dust on the interior of the bags which periodically may be shakendown into the bottom of the vessel 45 from which it is conveyed by theconveyor 49.

I may employ the bent pipe 35, shown in Figure 8, instead of thestraight pipe 35, shown in Figure 7. 'Ihis bent pipe has on it thenozzles 40 which function as the nozzles 40 heretofore described. Themodified form of pipe 35 is bent as shown in Figure 8 and has extendingtherefrom the nozzles 37 and terminates in a nozzle 38. Both pipes 35and 35" are rotatable 0 in the mill 26 to vary the angle at which theair i emitted from the nozzles strikes the lead lumps as they aretumbled in the mill 26. Moreover, the nozzles 37 as sliown in Figure 8will have theirouter ends raised and lowered on account of the bend inthe pipe 35" when the pipe 35" is rotated, thus varying the distancefrom' the outer ends of the nozzles 37 and the lead lumps as well as theangle at which the emitted air strikes the lead lumps.

I may attach a hand 64 to the pipe which may pass over a dial 65 toindicate on the outside of the mill 26 the position of the nozzlesinside the mill.

The operation of my device is apparent from the foregoing, but tosummarize the operation,` lead is deposited in the melting pot and whenmelted runs on to the revolving disc 2 into the groove 9 from which'itis scooped by the scoop 14 and caused to pass between the guide f`rollers 17, 18 and thence to the rollers 19',v 20', ME'

19, 20 to the revolving cutter 22 which cuts lumps of lead from the barand since the cutter is cam shaped on its periphery the" bar may Ill()be continuously moved towards the cutter and 15G the lumps will fallintoV the hopper 23 from which they' are conveyed by the hollow wormconveyor into 'the mill 26. Air is vforced by means of a blower, (notshown) or otherwise,

through the pipe and issues from the pipev 35 through the nozzles 40, 37and 38. The nozzles 37 and 38 blowthe powder out of the mill as soon asthe tumbling action breaks the powder from the lead lumps. The inclinednozzles 40 prevent the powder from coming back through the conveyor andhopper 23 and contaminating the atmosphere of the room in which theapparatus is situated. By reason of the oxidation of the lead lumps, theinterior of the mill becomes more or less hot depending on the amount oflead lumps therein, how fast it is operated, and the amount of airforced into the mill. It is desirable to cool this powder, which ismostly lead suboxide PbzO, as soon as possible to prevent furtheroxidation of the powder to litharge PbO, so it is carried into the waterjacketed vessel and cooled as rapidly as convenient thus preventingfurther oxidation of the powder. "The powder settling at the bottom ofthe vessel 45 is conveyed by the worm con' veyor 49 to the valve outlet50 and collects on the weighted valve 51 from which it is periodicallydumped into a receiving vessel. It will thus be seen that my apparatusconstitutes an eflicient mechanism for converting crude lead into leadpowder in a continuous operation.`

The mill should beoperated at a certain temperature limit to produce therequired uniform product.

This may be accomplished either by controlling the amount of chargeinthe mill or by regulating the amount of air. passing throughthe mill.But the temperature of the mill `can be more easily controlled by theamount' of charge of lead lumps into the mill. i

By using a thermo-couple 63 in the mill to indicate the temperature andemploying means to cut off the motor operating the lead bar making andfeeding mechanisms, when the mill temperature exceeds' a prescribedlimit the temperature may be kept down. On the other hand if thetemperature of the mill drops beyond its lower limit, the motoroperating the mechanism may be changed to regulate the feed `of the leadlumps into the mill, thus providing for operation of the mill at anyrequired range of temperature.

The position of the air nozzle with respect to the revolving mill isimportant to the effective removal of producedpowder and also to theamount of oxidation reaction. The distance of the end of the nozzles tothe moving contents in the mill is important as to the blowing oi effectof the forming powder.

The adjustable nozzles provide for varying the neness of the powder andthe amount of discharge product and also regulate the qualityv of theproduct especially the rateof oxidation of the powder. A weaker currentof air discharges only a ne product and the time of retaining the powderin the mill may be lengthened to let the product become more highlyoxidized.

The adjustable nozzles can be set at exactly the necessary position inmy mill to get the required product by the hand 64.

What Iy claim as my invention is:.

1. Apparatus for pulverizing lumps of material and converting the lumpsinto powder which comprises a revoluble tumbler mill having feeding andexhaust openings therein,

means to force air into the mill to blow the formed powder through theexhaust opening, and means including nozzles in the feed opening andinclined towards the mill to direct a portion of the incoming air in adirection through the feed opening back into the mill to prevent thepowder from backing out between the lumps as they are Afed to lthe millinto the surrounding atmosphere.

2. Apparatus for converting lead lumps into powder which comprises, arevolving tumbling mill lhaving'feed and exhaust openings therein,

means to force air into' the mill through the feed opening to blow theformed powder out of the mill through the exhaust opening, means to feedthe lumps into the mill` through the feed opening, and means to directsome of the incoming air in a direction through the feed opening blackbetween the lumps into the mill to' prevent the powder from backing outbetween the lumps as they are fed through the feed opening in the mill.

3. A revolving mill for tumbling particles of material to convert theparticles into powder, said mill having an entrance opening and anoutlet, a hollow conveyor for delivering the par. ticles through theentrance opening, a compressed air pipe extending through the hollowconveyor and having forwardly inclined nozzles thereon within' theconveyor to direct some of the incoming 'air between the lumps and back105 into the mill and other nozzles in the mill to direct the rest ofthe incoming air against the lumps in the mill.

4. A revolving mill for tumbling particles of material to convert theparticles into powder, said mill having an entrance opening axiallyarranged relatively to the `mill and an outlet opening, a conveyor fordelivering the particles through the entrance opening, a compressed airpipe extending through the entrance opening and havingnozzles inside themill' to blow the formed powder out of the mill outlet and also havingnozzles along the interior of the conveyor to prevent the formed powderbeing blown cut the mill entrance opening.

5. In combination a revoluble mill for tumbling particles of material toform a powder, said mill having an axially arranged outlet, means forsupplying compressed air to the mill to carry the powder through saidoutlet,` a vessel 125 attached to the outlet, said vessel having anoutlet at its top for the airand a restricted outlet at one side of itsbottom for the outlet of the powder, and means continuously operable forconveying'the powder to the outlet at 130 the side of the bottom, saidoutlet being normally closed but automatically openable by theaccumulated powder.

6. A material pulverizing mill comprising a revoluble portion having aninlet and outlet, 135 means for forcing airthrough the mill to removethe powder formed in the mill, a. vessel having a normally coveredopening in its bottom to receive the powder, said vessel being open 1 atits upper portion for escape of air and having 140 therein a bag offabric open at its bottom and closed at its top, the lower portion ofsaid vessel being water jacketed to quickly cool the powder as itsettles in said vessel, a conveyor for removing the powder to saidopening and an auto- 145 matically opened and closed cover for saidopening.

7. The process of making lead powder from lumps of lead comprisingfeeding the lumps simultaneously blowing air into the mill to carry theformed powder out of the mill as soon as it is formed on the lumps anderoded therefrom, and blowing air into-the mill through the mass oflumps as they enter the mill to prevent the powder from backing outthrough the mass of entering lumps.

8. The process of making suboxide lead powder which comprises feedinglumps of lead into a tumbling mill regulating the rate of feed of thelumps by the temperature of the mill, blowing out the powder resultingfrom tumbling the lead lumps in the mill as soon as the lead powder iseroded from the lumps and immediately cooling the suboxide powder bypassing it through a water cooled jacket to prevent further oxidation.

9. A revolvable mill for tumbling particles of material to convert theparticles into powder,

said mill having an axial entrance opening and outlet, a compressed airpipe extending through said opening for blowing air into the mill bentat an angle to itself and nozzles on the bent portion extendingdownwardly whereby turning of the pipe will raise and-lower the nozzles.

10. A revolving mill for tumbling particles of material to convert theparticles into powder, said mill having an entrance opening and anoutlet, a hollow conveyor for delivering the particles through theentrance opening, a compressed air pipe extending through the hollowconveyor into said mill and alternate pipe sections and sectionconnectors for lengthening said pipe, said connectors each having anozzle thereon and other nozzles extending from said pipe within theconveyor.

LYUHO S. ISHIMURA.

